diff options
| author | Xie He <xie.he.0141@gmail.com> | 2021-01-31 21:57:06 -0800 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2021-02-02 08:40:48 -0800 |
| commit | 88c7a9fd9bdd3e453f04018920964c6f848a591a (patch) | |
| tree | c23e141783bf91569d06000f5c3c26153b9ecbb5 | |
| parent | f418bad6ccfa6f0ef6ebc783ba72bb9c5738574f (diff) | |
| download | linux-88c7a9fd9bdd3e453f04018920964c6f848a591a.tar.bz2 | |
net: lapb: Copy the skb before sending a packet
When sending a packet, we will prepend it with an LAPB header.
This modifies the shared parts of a cloned skb, so we should copy the
skb rather than just clone it, before we prepend the header.
In "Documentation/networking/driver.rst" (the 2nd point), it states
that drivers shouldn't modify the shared parts of a cloned skb when
transmitting.
The "dev_queue_xmit_nit" function in "net/core/dev.c", which is called
when an skb is being sent, clones the skb and sents the clone to
AF_PACKET sockets. Because the LAPB drivers first remove a 1-byte
pseudo-header before handing over the skb to us, if we don't copy the
skb before prepending the LAPB header, the first byte of the packets
received on AF_PACKET sockets can be corrupted.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Acked-by: Martin Schiller <ms@dev.tdt.de>
Link: https://lore.kernel.org/r/20210201055706.415842-1-xie.he.0141@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rw-r--r-- | net/lapb/lapb_out.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/lapb/lapb_out.c b/net/lapb/lapb_out.c index 7a4d0715d1c3..a966d29c772d 100644 --- a/net/lapb/lapb_out.c +++ b/net/lapb/lapb_out.c @@ -82,7 +82,8 @@ void lapb_kick(struct lapb_cb *lapb) skb = skb_dequeue(&lapb->write_queue); do { - if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { + skbn = skb_copy(skb, GFP_ATOMIC); + if (!skbn) { skb_queue_head(&lapb->write_queue, skb); break; } |